ORIGINAL: planepounder
I had a hub come off once when The engine kicked back, the flywheel also flew off too! Put a piston stop (if you dont have one fill the cylinder full of small rope through the plug hole) put Loctite in the crank threads, put your prop on the hub and tighten the snot out of it . It will stay on then!
The key to that Locktite holding good also...is to have the parts cleaned ...do not have any oil reidue. Capt,n